1. Field of the Invention
This invention relates generally to the field of chemical reactions. More specifically, the invention relates to methods of making alkylene glycols incorporating high shear mixing.
2. Background of the Invention
Ethylene glycol is used as antifreeze in cooling and heating systems, in hydraulic brake fluids, as an industrial humectant, as an ingredient of electrolytic condensers, as a solvent in the paint and plastics industries, in the formulations of printers' inks, stamp pad inks, and inks for ballpoint pens, as a softening agent for cellophane, and in the synthesis of safety explosives, plasticizers, synthetic fibers (TERYLENE®, DACRON®), and synthetic waxes. Ethylene glycol is also used to de-ice airport runways and aircraft. Plainly, ethylene glycol is an industrially important compound with many applications.
Prior methods for hydrating alkylene oxides to the alkylene glycols include the direct hydration reaction without benefit of catalyst and the catalytic hydration of alkylene oxides using mineral acid catalysts. These mineral acid catalytic reactions are homogeneous thereby posing a problem for the commercial production of glycols since the catalyst is carried over into the product and must be separated. Present commercial processes use a noncatalytic hydration procedure which must use large ratios of water to alkylene oxide thereby presenting a problem of separation of the water from the finished product. This separation consumes large amounts of energy which recently has been the cause of much concern.
Recently, attempts have been made to discover a new catalyst for the hydration of alkylene oxides to the respective glycols. For example, other catalytic processes use tetramethyl ammonium iodide and tetraethyl ammonium bromide, or organic tertiary amines such as triethylamine and pyrridine. Despite a focus on the catalyst technology, little has been done toward improving the mixing of the alkylene oxide with the water phase to optimize the reaction.
Consequently, there is a need for accelerated methods for making alkyl glycols by improving the mixing of ethylene oxide into the water phase.